/Engine/Source/Developer/AnimationDataController/Public/AnimDataController.h
Inserts a new bone animation track for the provided name, at the provided index. Broadcasts a EAnimDataModelNotifyType::TrackAdded notify if successful. The bone name is verified with the AnimModel's outer targetUSkeletonto ensure the bone exists.
The index at which the bone track was inserted, INDEX_NONE if the insertion failed
virtual int32 InsertBoneTrack ( [FName](API\Runtime\Core\UObject\FName) BoneName, int32 DesiredIndex, bool bShouldTransact )